The hidden cost of our supermarket sea bass - and the effect it has on Senegal

The naturalist and broadcaster Chris Packham has condemned British supermarkets for a "dereliction of duty" over food labelling and sourcing, as a joint investigation by the Guardian and environmental website DeSmog reveals the retailers are selling fish from farms that import large quantities of fishmeal from Africa.

- Karen McVeigh

Factories in Senegal grind down small fish into meal that is sold to fish farms in Turkey, fuelling unemployment and food insecurity in Senegal by draining it of a food source relied on by local people - a cycle that connects directly to British consumers.

By examining trade data and shipping records and combining this with on-the-ground reporting in three countries, the investigation found Turkish-farmed sea bass and sea bream was being fed on fishmeal exported from three factories in Senegal: Omega Fishing and Africa Feed south of Dakar, and Afric Azote at Dakar port.

Local women who sell fish say they cannot compete on price with the factories, forcing increasing numbers of them out of work.

The research shows at least five UK supermarkets - Waitrose, Co-op, Aldi, Lidl and Asda - have sold sea bass or sea bream grown by one of Turkey's largest fish farmers, Kılıç Deniz, or its subsidiary Agromey, which sources fishmeal made from small Senegalese fish. The supplier lists, in-store labels and industry sources link these supermarkets to Kılıç's farms.

The retailers are supplied by two UK wholesalers - New England Seafood International and Ocean Fish, who use Kılıç and Agromey. These wholesalers have also sold sea bass or sea bream to Morrisons, Marks & Spencer, Sainsbury's and Tesco, the investigation found. The investigation was unable to establish whether that fish came to the wholesalers via Kılıç or another supplier.

Between them, these wholesalers have supplied supermarkets with 473 tonnes of fish raised by Kılıç or Agromey over the past four years, according to official data. That's enough fish to stack supermarket shelves with nearly 5m fillets.

The factories along Senegal's coastline used to rely on waste products, including fish heads and tails from the port, but now increasingly use more fresh "forage" fish, the mainstay of small-scale fisheries.